The regulation of fatty acid synthesis in animal cells and bacteria will be investigated. The fatty acid synthetase complex of animal tissues will be prepared in highly purified state. The various types of synthetase complexes will be isolated and characterized. Conditions will be developed for the dissociation of the synthetase complex into its various protein components. The activities and structures of these proteins will be investigated. Attempts will be made to reconstitute the complex from the individual subfractions. The regulation of lipid synthesis in E. coli will be investigated. In these studies fatty acid auxotrophs will be isolated and utilized. The effect of changes in fatty acid composition of membrane lipids on the structure and function of membrane associated enzyme activities will be investigated.